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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 127 records · Page 7Linked to original sources
PubMed1999

Plasmacytoma induction in specific pathogen-free (SPF) bcl-2 transgenic BALB/c mice.

Germ-free (GF) and specific pathogen free (SPF) BALB/c mice are refractory to plasmacytoma induction by pristane (McIntire and Princler, 1969, Byrd et al 1991). It was therefore suggested that MPC development may depend on antigenic stimulation. If so, it may conceivably act by preventing the apoptotic elimination of tumor precursor cells. We have tested this idea by elevating the apoptotic threshold by the introduction of a bcl-2 transgene. We have found that MPCs could be induced by pristane oil in transgene carrying SPF mice. An E mu activated bcl-2 transgene was introduced into SPF BALB/c mice. The mice were used after two backcrosses (BC-2). Pristane oil treatment was started at 4 to 6 weeks of age (3 x 0.3 ml via i.p. at monthly intervals). For each transgene carrier a transgene negative littermate was used as control. Fifteen of 24 (63%) transgene carriers developed plasmacytomas after latency periods between 67 and 146 days (mean = 112 +/- 30 days) after the first pristane injection. Five additional transgene carriers developed lymphoma (3 cases) or mixed MPC and lymphoma (2 cases). In contrast, no tumors developed in 16 transgene negative littermates that were kept > 300 days under observation. Karyotyping showed that 10/15 (66%) of the MPCs carried a T(12;15) translocation, 4/15 (27%) carried both T(12;15) and T(6;15) translocations in the same metaphase plate, and 1/15 (7%) was translocation free. A T(12;15) translocation was also detected in one of the 2 mice with mixed tumor type. Pristane treated bcl-2 transgenic C57B1/6 mice remained tumor free, although T(12;15) translocation carrying cells were found in the peritoneal fluid of 4/20 mice 176 days after pristane.

Animals↗
PubMed1999

A novel gene containing LIM domains (LIMD1) is located within the common eliminated region 1 (C3CER1) in 3p21.3.

Chromosomal deletions on 3p have been described in a large number of human tumors, suggesting the presence of a tumor suppressor gene(s). Using an experimental system, called the elimination test, we previously identified a 1 Mb segment, the common eliminated region 1 (C3CER1). C3CER1 was also covered by a PAC contig. Using the sequence of two overlapping PACs from C3CER1, we localized the human KIAA0028 cDNA, encoding the precursor of mitochondrial leucyl-tRNA synthetase. We also characterized a novel human LIM domain-containing gene (LIMD1) and its mouse ortholog (Limd1). LIM domains consist of a cysteine-rich consensus sequence containing two distinct zinc-binding subdomains, which mediate protein-protein interactions. The predicted protein sequences of the human and mouse genes reveal three LIM domains located at the C-terminal end, which indicates that they belong to the group 3 of the gene family encoding LIM motifs. We characterized the genomic structure of the human LIMD1 gene and assigned the mouse Limd1 gene to the chromosome 9F subtelomeric region. Both genes are ubiquitously expressed at the mRNA level. The LIM motif has been previously identified in many developmentally important factors from various eukaryotes. These factors have been shown to play a role in intracellular signaling, transcriptional regulation and cellular differentiation during development. The human C3CER1-located LIMD1 gene should therefore be further studied for its possible role in tumor suppression.

Amino Acid Sequence↗
PubMed1999

The effect of hysterectomy on the risk of an abnormal screening Papanicolaou test result.

OBJECTIVE: Our aim was to determine the risk of cytologic abnormality on a screening Papanicolaou test for women >/=50 years old with and without a uterine cervix. STUDY DESIGN: The effect of hysterectomy on abnormal screening Papanicolaou test rates was determined in a cross-sectional analysis of 21,152 women aged >/=50 years who had screening Papanicolaou tests between January and August 1995. We then conducted a nested 1:1 case-control study of 172 case patients and 172 age-matched randomly selected control patients from the cohort. To control for potential confounders, conditional logistic regression was used to assess the effect of hysterectomy status on the risk of an abnormal Papanicolaou test. RESULTS: Compared with age-matched women with a uterine cervix, those who had a hysterectomy had a 10-fold lower risk of a screening Papanicolaou test abnormality (odds ratio 0.09, 95% confidence interval 0.02-0.24). The risk was further reduced among women taking estrogens (odds ratio 0.02, 95% confidence interval 0.004-0.14) compared with women not using estrogens (odds ratio 0.14, 95% confidence interval 0.04-0.56). CONCLUSIONS: The reduced risk of Papanicolaou test abnormalities among women aged >/=50 years who have had a hysterectomy should be considered when individual patients are being counseled, screening guidelines are being formulated, and health care resources are being allocated.

Aged↗
PubMed1999

The multigene immunophilin family of Dictyostelium discoideum. Characterization of microsomal and mitochondrial cyclophilin isoforms.

The sequences of two cyclophilin (Cyp) isoforms from Dictyostelium discoideum have been determined. cyp2 is expressed as a 197 amino acid protein, which contains a 22 amino acid-long signal sequence, characteristic of endoplasmic reticulum localization signals, and that is cleaved in the mature protein. Mature Cyp2 has a molecular mass of 18 986 Da. The cyp3 gene encodes a 174 amino acid protein with a predicted molecular mass of 19 016 Da. Its sequence reveals no targeting sequence. From the MS analysis of affinity-purified cyclophilins from different subcellular compartments, we localized the previously described Cyp1 (Barisic K. et al., Dev. Genet. 12 (1991) 50-53) in cytosol, Cyp2 in microsomes and Cyp3 in mitochondria, respectively. The expression of cyp1 mRNA is constant during differentiation, whereas the mRNA level of both cyp2 and cyp3 is regulated and decreases steadily during development.

Amino Acid Sequence↗
PubMed1999

The mitochondrial adenine nucleotide translocator from Dictyostelium discoideum. Functional characterization and DNA sequencing.

The mitochondrial adenine nucleotide translocator (ANT) catalyses the exchange of ATP and ADP between the mitochondria and the cytosol. We have cloned and sequenced the gene encoding the Dictyostelium discoideum ANT (DdANT) and analysed its transcriptional regulation. The single copy D. discoideum ant gene encodes a protein of 309 amino acid residues with a predicted molecular mass of 33,469 Da and a pI of 9.85. These values are comparable to those of ANTs from mammals, insects and fungi. The long N-terminal extension characteristic of plant ANT is absent in DdANT. The protein coding region of the D. discoideum ant gene is interrupted by three introns. Polyclonal antibodies directed against the beef heart mitochondrial ANT or its C-terminal peptide recognized the D. discoideum protein. Northern blot analysis revealed that the expression of the D. discoideum ant gene decreased rapidly during the first hours of multicellular development but the amount of protein remained stable throughout differentiation.

Animals↗
PubMed1999

Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.

Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1999

Epstein-Barr virus infection and mitogen stimulation of normal B cells induces wild-type p53 without subsequent growth arrest or apoptosis.

Infection of human B lymphocytes with Epstein-Barr virus (EBV) in vitro induces a G0 to G1 transition followed by DNA synthesis and cell division. The virus activation of the cell cycle closely mimics the antigen-dependent normal B cell activation pathway. Infected B cells undergo blast transformation followed by the emergence of immortalized lymphoblastoid cell lines. Numerous cellular proteins are switched on in the infected cells, including p53. In view of the frequent association of wild-type p53 (wtp53) expression with growth arrest and apoptosis, p53 expression, cell viability (absence of apoptosis) and cell cycle progression at the single cell level during the first week after EBV infection were assessed. The rate of EBV infection was scored by EBNA-5 staining between 20 and 72 h after infection and varied between 20 and 25% of the cell population. All EBNA-5-positive blasts were p53-positive as well. Double staining for p53 and for DNA ends (TUNEL) revealed that p53-positivity and apoptosis were mutually exclusive. Quantification of the DNA content by Hoechst staining and computer-assisted image analysis showed that a fraction of the p53-positive blasts had a DNA content higher than 2N, indicating entry into the S/G2 phases. Double p53 and BrdU staining of the cells, pulse-labelled with BrdU, revealed that 65% of the p53-positive blasts were in S phase 3 days after infection. Similarly, B cell activation by CD40L and IL-4 induced p53 expression without any adverse effect on cell cycle progression. Therefore, the phenomenon is not EBV-specific but correlates with immunoblast activation.

Apoptosis↗
PubMed1999

Femtosecond measurements of the time of flight of photons in a three-dimensional photonic crystal.

We report on experimental measurements of the propagation behavior of short optical pulses in a three-dimensional photonic crystal in the visible spectrum. The propagation delay of 70 fs light pulses transmitted through a sample of a fcc synthetic opal at frequencies lying in a photonic stop band was measured directly using a time-of-flight technique. Taking into account spectral reshaping of the transmitted pulses as well as the residual frequency chirp of the incoming pulses, it is found that the pulses significantly slow down at the photonic band edges.

Journal Article↗
PubMed1999

ESCWGA/NASPE/P experts consensus statement: living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. Working Group of Arrhythmias of the European Society of Cardiology. North American Society of Pacing and Electrophysiology.

Current nomenclature for the AV junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with anteroposterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, whereas the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and AV nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and from the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions and establish the principles of this new nomenclature.

Atrioventricular Node↗
PubMed1999

Visualization of alternative Epstein-Barr virus expression programs by fluorescent in situ hybridization at the cell level.

Epstein-Barr virus (EBV) transforms human B lymphocytes into immortalized lymphoblastoid cell lines (LCLs). They regularly express six virally encoded nuclear proteins (EBNA1 to EBNA6) and three membrane proteins (LMP1, LMP2A, and LMP2B). In contrast, EBV-carrying Burkitt lymphoma (BL) cells in vivo and derived type I cell lines that maintain the BL phenotype express only EBNA1. During prolonged in vitro culturing, most EBV-carrying BL lines drift toward a more immunoblastic (type II or III) phenotype. Their viral antigen expression is upregulated in parallel. We have used fluorescent in situ hybridization to visualize viral transcripts in type I and III BL lines and LCLs. In type I cells, EBNA1 is encoded by a monocistronic message that originates from the Qp promoter. In type III cells, the EBNA1 transcript is spliced from a giant polycistronic message that originates from one of several alternative Wp or Cp promoters and encodes all six EBNAs. We have obtained a "track" signal with a BamHI W DNA probe that could hybridize with the polycistronic but not with the monocistronic message in two type III BL lines (Namalwa-Cl8 and MUTU III) and three LCLs (LCL IB4-D, LCL-970402, and IARC-171). A BamHI K probe that can hybridize to both the monocistronic and the polycistronic message visualized the same pattern in the type III BLs and the LCLs as the BamHI W probe. A positive signal was obtained with the BamHI K but not the BamHI W probe in the type I BL lines MUTU I and Rael. The RNA track method can thus distinguish between cells that use a type III and those that use a type I program. The former cells hybridize with both the W and the K probes, but the latter cells hybridize with only the K probe. Our findings may open the way for studies of the important but still unanswered question of whether cells with type I latency arise from immunoblasts with a full type III program or are generated by a separate pathway during primary infection.

Amino Acid Sequence↗
PubMed1999

Characterization of Dictyostelium discoideum cathepsin D.

Previous studies using magnetic purification of Dictyostelium discoideum endocytic vesicles led us to the identification of some major vesicle proteins. Using the same purification procedure, we have now focused our interest on a 44 kDa soluble vesicle protein. Microsequencing of internal peptides and subsequent cloning of the corresponding cDNA identified this protein as the Dictyostelium homolog of mammalian cathepsins D. The only glycosylation detected on Dictyostelium cathepsin D (CatD) is common antigen 1, a cluster of mannose 6-sulfate residues on N-linked oligosaccharide chains. CatD intracellular trafficking has been studied, showing the presence of the protein throughout the entire endocytic pathway. During the differentiation process, the catD gene presents a developmental regulation, which is also observed at the protein level. catD gene disruption does not alter significantly the cell behaviour, either in the vegetative form or the differentiation stage. However, modifications in the SDS-PAGE profiles of proteins bearing common antigen 1 were detected, when comparing parental and catD(-) cells. These modifications point to a possible role of CatD in the maturation of a few Dictyostelium lysosomal proteins.

Amino Acid Sequence↗
PubMed1999

Association between serum pepsinogen A and C levels, serum gastrin concentrations and Helicobacter pylori antibodies.

Pepsinogen A and C as well as gastrin were measured in the serum of 117 patients with rheumatic diseases. Moreover, the patients were divided up in groups by aids of a semiquantitative, rapid enzyme immunoassay for detection of Helicobacter pylori: 20 patients without H. pylori antibodies (AB) negative, 18 positive + (= weak AB-titre), 21 positive +2 (medium AB-titre), and 58 positive +3 (high AB-titre). The semiquantitative determinations of H. pylori-AB correlated with pepsinogen A, C and gastrin. Patients with H. pylori-AB positive +3 showed significantly higher values of pepsinogen C (p < or = 0.01) as well as pepsinogen A and gastrin (p < or = 0.05) than H. pylori-AB negative patients. Significantly increased levels of pepsinogen A (> 150 ng/ml) and C (> 25 ng/ml) were found to occur in 39% and 100% of patients with high H. pylori-AB titres. The measurement of serum pepsinogen C concentrations may provide additional diagnostic information of the extent of mucosal lesions in patients with positive H. pylori-AB titres treated with antirheumatic drugs. Our findings suggest that the semi-quantitative classification of positive AB-results can be useful in cases determining H. pylori infection and mucosal irritation if other investigations are not available.

Adult↗
PubMed1999

[Reducing pain by oral enzyme therapy in rheumatic diseases].

Proteolytic enzymes have analgesic, effects, besides the wellknown antiinflammatory and edema-reducing properties. These analgesic effects are based on the inhibition of inflammation and in addition to that on direct influences on the nociceptors. All that explains the therapeutical effects of such enzymes in degenerative-rheumatic and soft tissue rheumatic diseases in which inflammatory or immunologic processes are not in the forefront. In recent years a significant reduction of pain in various rheumatic diseases, concerning these aspects, was shown in several clinical studies. The clinical trial in patients with periarthritis of shoulder showed statistical equivalence of pain reduction, whether they were treated with phlogenzym or diclofenac. Likewise in the trial of patients suffering from painful osteoarthritis of the knee, there was a statistical equivalence of the pain-scores, comparing diclofenac and enzymes. The study of painful vertebral syndromes again resulted in equivalence of the treatment with NSAIDs compared to therapy with enzymes.

Adult↗
PubMed1998

Is conversion of solid into more anoxic ascites tumors associated with p53 inactivation?

Most solid tumors are unable to grow in the ascites form, unless selected by prolonged serial transfer of peritoneal fluid (Klein, 1955). Established ascites tumor cells grow under highly crowded, virtually anoxic conditions (Warburg and Hiepler, 1953). Hypoxia was recently identified as a powerful inducer of p53 dependent apoptosis (Graeber et al., 1996). We wished to examine whether the conversion of relatively well-vascularized solid mouse tumors into freely growing ascitic cell variants favors cell with mutated or deleted p53. We have sequenced exons 4-9 of p53 cDNA from two serially transplanted methylcholanthrene induced sarcomas (MCIM and MSWBS) that were available in the original solid and the gradually converted ascites form. We have also examined five additional solid tumors, four carcinomas and one sarcoma and six additional ascites tumors, five carcinomas and one sarcoma. Sequence analysis showed that all solid tumors carried exclusively wild type p53. Among the eight ascites tumors, five carried mutant p53 and three had only the wild type gene. In one of the two isogenic pairs, the original solid tumor line had only wild type, whereas the derived ascites line had only mutant p53. In the second pair, the solid tumor was wild type whereas the ascitic variant was heterozygous. The naturally occurring alternatively spliced p53 (p53as) mRNA was detected in all solid tumors, but not in five of the eight ascites tumors. Our findings indicate that conversion of solid into ascites tumors favors the selection of cell variants with mutated p53 and of cells that lack the alternatively spliced form of p53.

Animals↗
PubMed1998

The Canadian Registry of Atrial Fibrillation: a noninterventional follow-up of patients after the first diagnosis of atrial fibrillation.

The Canadian Registry of Atrial Fibrillation (CARAF) is a nondirected, follow-up study of 1,086 patients who are enrolled at 6 centers across Canada at the time of initial electrocardiographically documented diagnosis of atrial fibrillation (AF). Enrollment commenced in 1991 with an intended 10-year follow-up. Comprehensive baseline data, including clinical history, laboratory, and echocardiographic variables were collected. The patients were treated by their own referring physicians and CARAF did not direct their care. Detailed follow-up was performed at 3 months, 1 year, then yearly, with echocardiograms repeated every 2 years. Several studies, which evaluated patient populations, predictors of events, and cardiac structure and functioning, have been performed and are ongoing. Thyroid function was evaluated at baseline, and, of 707 patients evaluated, only 6 patients were found to be hyperthyroid. Symptoms during AF were evaluated and a profile of the types of symptoms and the predictors of symptoms was compiled. Antiarrhythmic drug use is being followed. Sotalol and propafenone were the most commonly used medications, with the use of antiarrhythmic drugs increasing with recurrence of AF. The use of anticoagulants was assessed. The overall use of warfarin was relatively low, but its use increased dramatically with the presence of various risk factors including congestive heart failure, hypertension, and previous stroke. The one risk factor that did not result in increased use of warfarin was hypertension. Therefore, CARAF was able to identify that hypertension appears to be under-recognized and undertreated in its risk for thromboembolic events. CARAF is just now reaching maturity, with the majority of patients having > or=4 years of follow-up. Therefore, extensive investigations are currently under way that will evaluate the baseline characteristics and utilize these as predictors of recurrence of AF, progression to chronicity, and the occurrence of major events such as stroke and death. A very large cohort of patients with serial echocardiograms over 4 years will permit an understanding of the progression of structural and valvular disease. Therefore, CARAF offers a unique opportunity for comprehensive, nondirected follow-up of patients from their initial diagnosis of AF.

Atrial Fibrillation↗